The overall goal of this project is to understand the mechanisms by which integrin adhesion receptors are affected by the microtubule (MT) cytoskeleton to coordinate cell migration. Much has been learned about the role of the actin cytoskeleton hi extending the leading edge during cell migration and hi establishing adhesive sites through integrin receptors to provide the traction necessary for cell migration. By comparison, our understanding of the cycle of integrin adhesion in the front and de-adhesion hi the rear is rudimentary. Microtubules have been implicated hi cell polarization required for cell migration and one of the emerging ideas for how they may contribute to cell migration, particularly of large, well-adherent cells, is through the control of integrin recycling from clustered sites of adhesion (termed focal adhesions). Dynamic MTs target focal adhesions and induced their disassembly by a process that we are just beginning to understand. Microtubules also contribute to recycling of endocytosed proteins and since MTs themselves become polarized hi migrating cells, the return of endocytosed integrin to the leading edge may be critical for maintaining the directional polarity of migrating cells. We have developed an assay that allows use to dissect the key steps hi the MT-induced disassembly of focal adhesions and the recycling of integrins to form new adhesions. We have used this assay to identify dynamin, clathrin and focal adhesion kinase as key participants hi focal adhesion disassembly, suggesting that integrins may be endocytosed during focal adhesion disassembly. We will pursue this hypothesis further by examining the dynamics of clathrin and dynamin during focal adhesion disassembly, the role of clathrin adaptor proteins and focal adhesion components in targeting clathrin to focal adhesions, and the possibility that MTs deliver factors to the activity of clathrin and dynamin at focal adhesions. We will also explore the role of microtubules in recycling disassembled focal adhesion components and determine whether known endocytic recycling pathways are involved, the role of MT motors in the process and how residence of integrins in focal adhesions may activate them for recycling back to the membrane after they are disassembled. Understanding how the integrin adhesion system cross-talks with the microtubule cytoskeleton will provide new information on the fundamental ways cells integrate their cytoskeletal systems during cell migration, a process of importance for development, wound healing, inflammation and metastasis.